Technical Field
This disclosure relates to medical devices, and more particularly to medical devices that monitor patient cardiac function.
Discussion
Many cardiac patients have conditions which can result in excessively fast or erratic heartbeats. If not treated promptly, ventricular fibrillation or certain ventricular tachycardias can result in a fatal outcome. If such arrhythmias are promptly detected and treated, such as by electric shock defibrillation, the result of such an attack can often be minimized. Treatment is normally needed within a few minutes of the onset of the condition to be effective. Therefore, it can be critical to accurately detect such a condition as soon as possible after its occurrence.
Ventricular tachycardia and ventricular fibrillation are two heart rhythms that are treatable by an electrical shock properly applied to the body of the patient. Both of these conditions sometimes occur along with a detectable high heart rate in the patient. Utilization of a threshold heart rate will detect these two conditions in many cases and treatment can begin. Unfortunately, other conditions such as, for example, supraventricular tachycardia also have a high heart rate and these are not treatable by electric shock therapy. Therefore, utilizing a detection methodology which relies only on heart rate to institute treatment may cause treatment to be rendered under conditions where shock therapy may be inappropriate.